1. Field of the Invention
The present disclosure relates to wavefront sensing, and more particularly to using wavefront sensing with an enhanced pixel.
2. Description of Related Art
Wavefront sensors are used to correct aberrations in images. For example, images generated during air travel can be subjected to turbulence that can cause the images to be laden with aberrations. Wavefront sensing can be applied to such aberration laden images to detect and remove aberrations and output an aberration-free image.
For example, a telescope can enlarge an image during air travel, including when turbulence occurs. The turbulence can add aberrations to the enlarged image. The enlarged image can be output to optics including one or more lenses that modify the enlarged image, such as to provide focus or change the size of the image. The optics can output the image to a detector having an array of imaging pixels that senses the image and generates a plurality of electrical signals, such as to form an analog image that represents the image output by the optics. The detector can include a wavefront sensing circuit that detects aberrations in the electrical signals that represent the sensed image, such as aberrations caused by the turbulence. A reconstruction module can use the detected aberrations to reconstruct the sensed image by correcting the detected aberrations and outputting an aberration-free image.
Wavefront sensing applications typically use pulsed laser illumination with pulse durations on the order of tens of nanoseconds. The wavefront sensing circuit must be able to sense these high-speed signals while imparting low noise. High speed and low noise are often conflicting parameters in a photodetector pixel design.
Wavefront sensing pixels that use capacitive transimpedance amplifier (CTIA) pixels take advantage of the high-speed nature of CTIA pixels. However, CTIA pixels are susceptible to noise due to magnification of amplifier noise at an output node. An integration capacitor positioned along a feedback path of an input buffer must have a very low capacitance due to noise considerations. The restriction on the size of the capacitance of the integration capacitor limits the intensity of the signal that can be sensed before saturation. Additionally, a CTIA pixel designed for high speed detection would have a high bandwidth and integrate noise over a wide range of frequencies, resulting in a tradeoff between noise performance and pixel speed.
While conventional methods and systems have generally been considered satisfactory for their intended purpose, there is still a need in the art for pixels to perform wavefront sensing with reduced noise and with increased sensitivity capable of sensing short-duration laser pulses. The present disclosure provides a solution for this problem.